【作者】 唐勇；

【导师】 龙炳清； 徐盛明；

【作者基本信息】 四川师范大学 ， 环境科学， 2007， 硕士

【摘要】 在污水处理技术领域,TiO₂光催化水处理技术因具有效率高、能耗低、适用范围广、反应条件温和、无二次污染和无毒副作用等优点而被认为是最有前景的有机污染物废水处理技术之一。直接应用TiO₂悬浮体系处理污水要比基体负载固定TiO₂体系有更高的处理效率,但是悬浮态的TiO₂存在着回收困难的问题,如直接排放,不仅浪费资源,而且会再次污染环境。对此,一些科研工作者采用Fe₃O₄、γ-Fe₂O₃、γ-Fe₂O₃ - SiO₂等磁性颗粒为磁性内核,直接在这些颗粒上面包覆TiO₂或者先包覆SiO₂中间层再包覆TiO₂,制备得到了磁性TiO₂光催化剂,这些催化剂既具有良好的催化活性,又可以通过磁力回收,这在一定程度上解决了悬浮态TiO₂难以回收的问题。但是这些磁性光催化剂存在着一些缺陷如热稳定性低、颗粒团聚严重、磁响应在包覆后大幅下降等,严重制约了它们的应用。针对以上问题,我们首先采用了共沉淀-水浴法和溶胶-凝胶法制备了具有较好形貌的Mn_xZn_1-xFe₂O₄软磁体颗粒,该软磁体颗粒能够在700oC以内保持良好的磁性,具有很高的热稳定性;采用烧结法制备了含Mn_xZn_1-xFe₂O₄的磁性氧化物。以这两种颗粒为磁性内核,采用溶胶-凝胶法在颗粒上包覆SiO₂中间层,得到了单分散球形的SiO₂/(含Mn_xZn_1-xFe₂O₄氧化物)和形貌较好的SiO₂/(Mn_xZn_1-xFe₂O₄)复合物磁性催化剂载体,然后采用水热法在这两种载体上包覆纳米TiO₂ ,最终得到了TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄)和TiO₂/SiO₂/(含Mn_xZn_1-xFe₂O₄氧化物)磁性光催化剂颗粒。采用XRD、SEM、VSM等对其分析,结果表明:TiO₂/SiO₂/(含Mn_xZn_1-xFe₂O₄氧化物)呈单分散球形,粒径约在500nm左右,具有明显的壳-核结构,磁性内核被SiO₂严密包覆,锐钛型TiO₂均匀负载其上;TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄)则无规则形貌,团聚较为严重,它们均具有灵敏的磁响应性。这两种催化剂对毛用活性黄的降解实验表明,它们都具有较高的光催化活性,有良好的应用前景。更多还原

【Abstract】 The technique of titanium dioxide photocatalytic oxidation is a new kind of water treatment process with great potential application for protecting environment and it has become a hot research area now. As a photocatalyst, titanium dioxide has high catalyzed activity, excellent chemical stability, innocuity, low option to organics degradation and fully mineraling organics to CO2 and H2O. Although many researchs have proved to nanometer TiO₂ can decompose most organic pollutants into inorganic substances under UV irradiation, a problem which TiO₂ particles are difficult to be separated from the treated water restrict nanometer TiO₂ to cosmically apply. Many studies have been carried out to obtain magnetic titanium dioxide photocatalysts, in which the nanometer TiO₂ could be deposited onto the surface of mangnetic material such as Fe3O4,γ-Fe2O3,γ-Fe2O3 - SiO₂ and soon. But it is well known that Fe3O4,γ-Fe2O3 andγ-Fe2O3 are thermally instable, weak mangnetic property after been costed nanometer TiO₂ particles, quite easy to aggregate, and will transform into material without magnetic property at lower temperature.In this paper, Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) was separately prepared by both coprecipitation -hydrothermal method under 90℃and sol-gel method synthesis, and the compound contained Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) was obtained with sintered under different temperature. The Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) and compound contained Mn Zn ferrite (Mn_xZn_1-xFe₂O₄) act as the magnetic core of composite photocatalyst, and then they were in turn coated with uniform layers of SiO₂ and amorphous titanium dioxide by the sol-gel and hydrothermal methods to get the photocatalysts of TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄) and TiO₂/SiO₂/（ the compound contained Mn Zn ferrite）. The particles of TiO₂/SiO₂/（ the compound contained Mn Zn ferrite） with about 500nm has abviously structure of core-shell by the analysis of XRD and SEM and excellent stable. In addition VSM has showed that the magnetic property of products is well after the two steps of coating.Finally, it was found that the TiO₂/SiO₂/(Mn_xZn_1-xFe₂O₄) and TiO₂/SiO₂/（ the compound contained Mn Zn ferrite） calcined at 450℃for 1h showed higher photocatalytic activity than that of pure TiO₂（150nm, Pangang group） by the photocatalytic degradations of Reactive Yellow 39, suggesting they be very promising .更多还原